Over center cam engaged clutch



April 8, 1952' N. E. RISK ETAL 2,591,373

' OVER CENTER CAM ENGAGED CLUTCH Filed Jan. 23, 1948 v a Sheets-Sheet'l ATTORNEY April 1952 N. E. RISK ETAL 2,59 ,873 I OVER CENTER CAM ENGAGED CLUTCH Filed Jan. 2;, 1948 v 3 She ets-Sheet a ""ATToRNzY E. RISK ETAL {112,591,873 OVER CENTER CAM ENGAGED CLUTCH j;:"

April 8, 1952 Filed Jan. 25; 194

Patented Apr. 8, 1952 OVER CENTER CA M ENGAGED CLUTCH NormanE. Risk, Charles A. Ramsel, and Russell 0. Williams, Peoria, Ill., assignors to Caterpillar Tractor 00., Peoria, 111., a corporation of California Application January 23, 1948, SerialNo. 3,866

I This invention relates to clutches in general and more particularly to main drive clutches such as are employed between the engine and a trans- .m-issionnf a tractor or like vehicle.

In clutches of this type it is desirable to have the :overall length of the clutch mechanism as. short as possible in order to conserve space. It

is also important to permit ready accessfor servicing and adjustment of the clutch, as well as to provide some means of warning the operator whenthe clutch is in need of adjustment.

It is therefore an objectof the present invenconstruction adapted to be supported by the hywheel of an internal combustion engine orthe -means associated with the wedge action to jreduce friction to a minimum. .A further object is to provide centrifugally actuated means tendi l to hold the clutch in disengagement and serv- --ing also as an indicator of. wear on th clutch discs. 6

Further objects and advantages of the inven- 2 Claims. (Cl. 1$2-93) tion to provide a clutch of improved light weight tion are made apparent in the following description wherein reference is made to the accom= painying drawings.

In the drawings:

. -Figl is a vertical sectional View of .a clutch embodying this invention;

Fig. 2 is a fragmentary sectional view of a por- Fig. 6 is an enlarged fragmentary sectional view taken-along the line VI-VI of Fig; 4.

The general arrangement of a clutch embodying the present invention is illustrated as being associated with an internal combustion engine.

In Fig.1 of the drawings a flywheel 2 is shown as secured to a flange 3 of an engine crankshaft 4 bymeans of capscrew 5. A driven shaft to whichjpower is transmitted by th clutch is illus't'rated at 6 as having one endjournalled in a "bearing 1 disposed in a centrally located recess in the flywheel and also as being supported ina bearing 3 disposed in a housing 8 enclosing the clutch. The extending end of the driven shaft *may be connected to any .suita-blepower absorbing mechanism such as a vehicle transmission (not shown) Substantially the entire weight of :the clutch is carried by the flywheel and it is for this .Pu-rpose'lthat a plate II and a collar -I2 are both secured to the fiy-Wheelzby means of cap screws I 3.

nection therewith.

2 The flywheel is of a hollow 0r cupped construction for the reception of a pressure plate I4 and a clutch driven disc IS. The driven, .disc is rig.-

idly secured as by rivets H to a'hub I8 splined for sliding movement on the shaft 5,. The OP- posite faces of the disc l6 are preferably covered with a frictional surfacing material such as is illustrated at 19.

An inwardly extending annulus 2| is formed integrally with the supporting plate .I I, formin a cup-like chamber for the reception Of the pressure plate I4. The inner circumference of the annulus 2| is toothed to mesh with teeth formed on the periphery of the pressure plate. Byvirtue of this toothed or splined connection, the pressure plate is supported by and-rotated with the supporting plate I I but is free to be moved axially to effect engagement and disengagement with the driven disc I6. Such axial movement is effected by urging rollers 22 between a pair of opposed and relatively inclined ramps 23 and 24. The inclined ramp are formed integrally with the pressure plate !4 and the ramp 24 is formed as a part of an adjustable collar 25. Both ramps are annular in shape and are disposed concentrically with relation to the main axis of the clutch. There are a plurality of rollers 22 spaced equally throu hout the .circular space between the opposed ramps. Suitably spaced Openings 26 are provided in the supporting plate I I to accommodate the rollers in their positions between the inclined ramps Y23 and 24. The adjustable collar 25 is threaded into a'rearwardly extending hub portion .2? formed integrally with the clamping collar I2. The collar 25 is adjustable with relation to the hub 27 by virtue of its threaded con-- 7 A capscrew 28 extending through a split portion. '29 in the hub 21 serves to secure the collar 25 in its adjusted osition.

Each of the rollers 22 is journal'led' about a pin 3| supported in one end of a bifurcated link 32 (see also Figs. 2 and 3). The opposite end' of the link is pivotallyconnected by means of a pin 33 to a radially extending car 34 formed integrally with a sliding collar 35. The slidin collar 35 is supported on a pair of spaced bearings 36, ,such bearings being journalled about an x n ed hub p rtion .3 formed int grally wit the supporting plate I I. A pin 38 isjrigidly'secured to the plate I Land its extending end is received in a recessf39 provided in the sliding collar. By virtue of this connection the sliding collar is rotated with the plate I I and at the same time permitted to move axially with relation thereto. Disposed about the sliding collar is a clutch throwout bearing 4!, the inner race .of

which is rigidly secured to the sliding collar, while the outer race is retained in aslid-ing yoke .42 by means of a retainer plate I3.

The yoke 42 is connected to any suitable actuthe flywheel. Movement of the sliding collar 35 toward the flywheel forces the rollers 22 outwardly between the ramps 23' and 24. This results in the pressure plate I4 being moved toward the flywheel into frictional engagement with the driven disc 55.

In order to retain the clutch in the engaged position the links 32 are moved to an overcenter position, such as is illustrated in Fig. 1 of the drawings. Further movement of the sliding collar toward the flywheel is limited by a number of fingers, one of which is illustrated at 46. The fingers 46 are formed integrally with the sliding collar 35 and extend through the apertures 26 terminating in a position to abut the pressure plate M. Movement of the links 32 to their overcenter positions is permitted by a relatively long thin walled section 4'! provided in the collar 12 which section affords sufficient resiliency to permit the overcenter action of the rigid links and at the same time to insure even bearing of the pressure plate on the driven discs [6.

When the clutch is moved to a disengaged position, such as is illustrated in Fig. 2 of the drawings, the pressure plate is urged away from the flywheel by means of a number of radially spaced springs, one of which is illustrated at 48. Each spring circumscribes a stud 49 having a threaded cpnnection with the pressure plate I4 and is interposed between a retainer 56 threaded to the stud and a shoulder formed at the end of a recess 54 in the supporting plate 1 I.

As is best illustrated in Figs. 2 and 3 of the drawings, a counterweight 53 forms a part of each of the links 32. The presence of the counterweight 53 so disposes the center of gravity of the link assembly that as the result of centrifugal "force the assembly urges the clutch toward the disengaged position. The counterweights 53 not only serve to urge the clutch to the disengaged position but may be of such a size as to cause the clutch automatically to disengage when wear on comes greater until the rollers 22 are permitted to swing away from their overcenter position under centrifugal force. This is of particular advantage in that it prevents the operator from employing the clutch when it is in need of adjustment. The manner in which the clutch when worn or poorly'adjusted is thrown out of engaged position may best be understood by reference to Fig. 1 wherein the clutch is shown engaged and the weights 53 are creating a centrifugal force tending to swing the links 32 toward the right. Because the links are in overcenter position with the centers 3! of the rollers advanced leftward with respect to the pivots 33, the rightward swinging movement of the links must be accompanied by a slight downward movement of the roller 22 which would, of necessity, spread apart the ramp 23 and 24. If the clutch is properly adjusted, this force created by the counterweights 53 is insufficient to spread the ramps apart. However, if the friction discs have worn, the resistance to spreading of the ramps 23 and 24 is less and the weights 53 will function to disengage the clutch.

tiple plate clutch in which parts corresponding 4 to those shown in Fig. 1 are identified with corresponding reference characters. In this modification, a pair of driven discs 56 are illustrated as having splined connection with a hub member 51, the hub being disposed about and having a splined connection with the driven shaft 6. A pair of pressure plates 58 and 59 are associated with the driven discs 56, and are free to move axially but keyed against rotation relative to the flywheel by means of radially extending lugs 6| formed in the periphery of the pressure plates,

- and received in spaced slots 63 formed in the fiywheel. A rearwardly extending hub 64 is formed integrally with the pressure plate 58 and is supported by a pair of bearings 65 rotatable on the driven shaft 6. The sliding collar 35 is journalled directly on the circumference of the hub 64.

As also shown in Figs. 5 and 6 of the drawings, a pair of resilient link members 66 are pivotally connected by means of pins 61 to each of the extending ears 34 of the sliding collar 35. The opposite ends of the resilient links support a pin 66 upon which three rollers 69, I0, and II are journalled. The rollers are disposed between the inclined ramp 24 associated with the adjustable collar 25 and the inclined face of a pressure shoe I2, rigidly secured to the rear face of the pressure plate 58. Engagement of the clutch is effected by urging the rollers between the inclined ramps in the manner previously described. However, in order to prevent a sliding action between the rollers and either of the inclined ramps, the rollers 69 and H are of a smaller diameter than the roller 16 so that only the roller 10 is in contact with the ramp 24. A relief 13 (Fig. 6) is formed in the shoe 12 providing adequate clearance so that the roller 16 does not contact the shoe. By virtue of this construction, the roller 16 is in contact only with the ramp 24 and the rollers 69 and H are in contact only with the inclined face of the shoe [2, thus permitting free rolling action as the rollers move across their respective inclined faces.

Disposed within each of the recesses 63 in the periphery of the flywheel is a counterweight 14. The counterweight is pivotally mounted on a pin 15 and is provided with an extending finger 16 which contacts the lug 6! formed in the periphery of the pressure plate 58. When the clutch is rotating the counterweights pivot about their supporting pin urging the clutch toward a disengaged position. The counterweights serve to retain the clutch in a disengaged position in opposition to the tendency that would be present in the links and rollers under centrifugal action to effect engagement of the clutch were the counterweights not used. The counterweights serve also to urge the pressure plate 58 out of frictional engagement with the driven discs 56 when the clutch is disengaged.

We claim:

1. In a friction disc type clutch, a pressure plate movable to engage the clutch, a surface inclined relative to the pressure plate, rollers disposed between said surface and the pressure plate, pivoted links supporting said rollers, and means to swing said links in a direction to move the rollers into a wedging position for advancing the pressure plate to a clutch engaging position, said links being arranged to assume an overcenter position relative to their pivotal support when the clutch is engaged and weights on said links tending to swing them under centrifugal action away from their clutch engaging position.

2. In a disc type clutch which includes a. pressure plate for imparting clutch engaging pressure to the discs, a surface inclined relative to a surface on the pressure plate, rollers disposed between the relatively inclined surfaces, pivoted links supporting the rollers, means to swing said links for moving the rollers into a wedging position between said surfaces and into an overcenter position for engaging the clutch, and weights on said links for creating a centrifuga1 force tending to disengage the clutch but insufiicient to dislodge the links from their overcenter' position when the clutch discs are adjusted for required friction.

NORMAN E. RISK.

CHARLES A. RAMSEL.

RUSSELL C. WILLIAMS.

6 REFERENCES CSIITED UNITED STATES i 'hrnN rs Number Name Date 834,499 Sturtevant Oct. 30, 1906 1,233,561 Dorrfeld July 17, 1917 1,272,745 White July 16, 1918 1,279,243 Bruce et a1 Sept. 17, 1918 1,306,302 Cooper June 10, 1919 1,392,932 Griffin Oct. 11,1921 1,553,101 Osborn Sept. 8, 1925 1,923,438 Hughes Aug. 22, 1933 2,033,835 Lansing Mar. 10, 1936 2,170,171 Wemp Aug. 22, 1939 2,185,714 Scherer Jan. 2, 1940 

